2. Patients should have demonstrated to have failure to therapy to one FDA-approved TKI (currently imatinib, dasatinib, and nilotinib are approved as frontline therapy), defined as per European leukemiaNet (ELN) recommendations: 1. Less than complete hematologic response (CHR) at or beyond 3 months; 2. No cytogenetic response at or beyond 6 months; 3. Less than PCyR (Ph+ >35%) at or beyond 12 months; 4. Less than CCyR at or beyond 18 months; 5. Loss of response or development of mutations or other clonal chromosomal abnormalities at any time during TKI treatment; 6. Intolerance to imatinib, dasatinib or nilotinib defined as grade 3 or 4 toxicity, or persistent grade 2 toxicity despite optimal management including dose adjustment, or in a patient where dose reductions are considered to be not in the patients best interest to obtain or maintain an adequate response. Intolerant patients should not have achieved or have lost major cytogenetic response at the time of enrollment.